Documentation/filesystems/dax.rst

47  2. There exists a persistent flag `FS_XFLAG_DAX` that can be applied to regular
51  3. If the persistent `FS_XFLAG_DAX` flag is set on a directory, this flag will
57  4. There exist dax mount options which can override `FS_XFLAG_DAX` in the
61     ``-o dax=inode``  means "follow `FS_XFLAG_DAX`" and is the default.
63     ``-o dax=never``  means "never set `S_DAX`, ignore `FS_XFLAG_DAX`."
65     ``-o dax=always`` means "always set `S_DAX` ignore `FS_XFLAG_DAX`."
76       Modifications to and the inheritance behavior of `FS_XFLAG_DAX` remain
83     a) Setting the parent directory `FS_XFLAG_DAX` as needed before files are
88     c) Changing the `FS_XFLAG_DAX` flag on existing regular files and
92  6. When changing the `S_DAX` policy via toggling the persistent `FS_XFLAG_DAX`
100 There are 2 per-file dax flags.  One is a persistent inode setting (`FS_XFLAG_DAX`)
104 `FS_XFLAG_DAX` is preserved within the filesystem.  This persistent config
108 New files and directories automatically inherit `FS_XFLAG_DAX` from
109 their parent directory **when created**.  Therefore, setting `FS_XFLAG_DAX` at
157 value of `FS_XFLAG_DAX` and the filesystem's dax mount option.
166 Setting the `FS_XFLAG_DAX` flag (specifically or through inheritance) occurs even
176 rather than the persistent `FS_XFLAG_DAX` flag. That is, whether DAX shall be
179 on the persistent `FS_XFLAG_DAX` flag on the host.
181 It is still supported to set or clear persistent `FS_XFLAG_DAX` flag inside